typedef Compare = int Function(Object a, Object b);


class SortColletion{
  Compare compare;
  SortColletion(this.compare);
}

int sort(Object a,Object b)=>0;

main(){
  SortColletion sortColletion = SortColletion(sort);
   assert(sortColletion.compare is Function);
   assert(sortColletion.compare is Compare);
  print("xiong");
}